1. Field of the Invention
The present invention relates to a cylinder alignment monitoring system for a mast or derrick in order to monitor alignment of the cylinders during operation to move the mast or derrick between a storage and transportation position and an upright use position.
2. Prior Art
A mast or a derrick of a rig, such as a subterranean drilling rig, supports a block and tackle or similar equipment over a well hole in order to raise and lower drill bits, elongated drill pipes and various other equipment utilized downhole. Drilling rigs can be utilized for mineral exploration drilling, oil well drilling, natural gas drilling and water well drilling. The mast or derrick may vary in height but can often extend up to 200 feet.
Once one drilling project has been completed, the drilling rig is disassembled, then transported to a new location, and then re-assembled for use.
The mast or derrick is typically moved between a substantially horizontal storage or disassembly position and an upright use position by rotating the mast or derrick at the base approximately ninety degrees (90°).
The mast or derrick will be hingedly connected to equipment on the ground, such as a drilling floor supported by a substructure.
The mast or derrick will typically have four sides, or three sides with one open side. In one arrangement, the mast or derrick includes a pair of opposed sides, a back face and an open front. A pair of cylinders, such as hydraulic cylinders, are utilized to move the mast or derrick between the substantially horizontal position and the upright use position. In order to raise and lower the mast or derrick properly, the pair of hydraulic cylinders should operate in tandem. If the hydraulic cylinders do not operate in tandem, the mast or derrick may not be raised or lowered properly. The mast or derrick itself may become out of alignment. In extreme cases, damage can be done to the mast or derrick, as well as to the rig itself.
In the past, personnel have visually monitored the raising or lowering of the mast or derrick in order to confirm that the hydraulic cylinders are operating in tandem.
Accordingly, it is desirable to provide a cylinder alignment monitoring system for a mast or derrick in order to monitor alignment of the cylinders during movement of the mast or derrick between a storage and transportation position and an upright position.